GENERAL STATEMENT



GENERAL STATEMENT

The Trinidad and Tobago Bureau of Standards (the Bureau) is a body corporate established under the authority of the Standards Act No. 18 of 1997 (herein after referred to as the Standards Act).

In accordance with the Standards Act, the Bureau shall promote and encourage the development and maintenance of standards and further shall establish standards for the following: to improve goods produced or used in Trinidad and Tobago; to ensure industrial efficiency and development; to promote public and industrial welfare, health and safety; and to protect the environment.

The Bureau develops standards through consultation with relevant interest groups, and public comment is invited on all draft standards before they are declared as Trinidad and Tobago Standards in accordance with the provisions of the Standards Act.

The Bureau is the legal custodian of the Trinidad and Tobago Standard Mark, which is issued in accordance with the Standards Act. When a Trinidad and Tobago Standard Mark appears on any product, or in connection with any service, process or practice, it provides assurance that such a product, service, process or practice conforms to a Trinidad and Tobago Standard.

The Bureau’s Standards Information Centre maintains a reference library of standards, including local, regional and international standards and is the national node of the International Organization for Standardization Information Network (ISONET). The Centre also acts as the sales agent for the publications of foreign and international standards organizations.

NOTE In order to keep abreast of progress in the industries concerned, Trinidad and Tobago Standards are subject to periodic review. Suggestions for improvements are welcome.

AMENDMENTS ISSUED SINCE PUBLICATION

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ATTACHMENT PAGE FOR TTBS AMENDMENT SHEETS

TRINIDAD AND TOBAGO BUREAU OF STANDARDS

PNEUMATIC PASSENGER CAR TYRES ( SPECIFICATION

(3rd Revision)

__________________________________________________________________________

The Specifications Committee responsible for the formulation of this Trinidad and Tobago Standard is as follows:

SPECIFICATIONS COMMITTEE FOR PNEUMATIC

PASSENGER CAR TYRES

Members Representing

Mr. Robert Cudjoe (Chairman) Ministry of Works and Transport - Mechanical Services Division

Mr. Ravi Jaimungalsingh Advanced Tyre Systems Limited

Mr. Randolph De Peza Intercity Taxi Drivers Association

Mr. Aloysius Bereaux Automotive Components Limited

Mr. Ian Arrindell Automotive Dealers Association of Trinidad & Tobago

Mr. Malcolm Bater Automotive Dealers Association of Trinidad & Tobago

Mr. Donald Mackenzie Mileage Mack Limited

Mr. Patrick Romano Ministry of Trade and Industry and Consumer Affairs

Mr. Indar Singh Trinidad and Tobago Used Tyres Importers Association

Mr. Cecil Sequea Ministry of Works and Transport - Licensing Office

Mr. Steve Williams Trinidad & Tobago Bureau of Standards

Mr. Ian Eccles (Technical Trinidad & Tobago Bureau of Secretary) Standards

Contents

Foreword 1

Introduction 2

1 Scope 3

2 Normative references 3

3 Terms and definitions 3

4 Tyre designation 3

4.1 Dimensional and constructional characteristics 3

4.2 Nominal section width 3

4.3 Nominal aspect ratio 4

4.4 Tyre construction code 4

4.5 Nominal rim diameter code 4

4.6 Service conditions characteristics 4

4.7 Other service characteristics 5

5 Requirements for new tyres 5

5.1 General 5

5.2 Physical dimensions 5

5.3 Tubeless tyre resistance to bead unseating 6

5.4 Tyre strength 6

5.5 Tyre endurance 6

5.6 High speed performance 6

6 Sampling and testing to determine compliance 6

6.1 General 6

6.2 Sampling and testing 6

6.3 Compliance 7

7 Presentation, inspection and selection of used tyres 7

7.1 Presentation of used tyres for inspection 7

7.2 Inspection of used tyres 7

7.3 Selection criteria for used tyres 7

8 Non-conforming tyres 8

9 Storage 8

10 Labelling requirements 9

Annex C (normative) Test method for determining the average tread depth of used passenger car tyres 16

Annex D (normative) Tables and figures 18

Annex E (informative) Recommended information to be supplied by the purchaser and the manufacturer or supplier 27

E.1 Recommended information to be suplied by the purchaser 27

E.2 Recommended information to be supplied by the manufacturer or supplier 27

Figures

Figure D.1 — Bead unseating fixture 23

Figure D.2a — Bead unseating block 24

Figure D.2b — Bead unseating block 25

Figure D.3 — Measurement of tread depth for uniform wear 26

Figure D.4 — Measurement of tread depth where irregular wear is exhibited 26

Tables

Table D.1 — Rim code diameter 18

Table D.2 — Correlation between load index (LI) and tyre load carrying capacity (TLCC) 19

Table D.3 — Correlation between speed symbol and speed category 20

Table D.4a — Minimum breaking energy values for radial ply tyres 20

Table D.4b — Minimum breaking energy values for bias ply tyres 21

Table D.4c — Minimum breaking energy values for tyres with 60 psi maximum permissible

inflation pressure 21

Table D.5 — Test inflation pressures 22

Table D.6 — Applied load and respective time 22

Foreword

These requirements were declared a Trinidad and Tobago Standard with effect from ……………., after the draft finalised by the Specifications Committee on Pneumatic passenger car tyres was approved by the Bureau.

The Committee has recommended that this standard be declared a compulsory standard to protect the consumer or user against danger to safety.

This standard will become effective as a compulsory standard on a date to be notified by the Minister responsible for trade and industry in a Notice to be published in the Trinidad and Tobago Gazette, as required by the Standards Act No. 18 of 1997.

This third revision cancels and replaces the second revision (TTS 266: 2002) which has been technically revised.

In formulating this standard considerable assistance was derived from the following:

International Organization for Standardization Standard,

ISO 4000-1:1989 Passenger car tyres and rims - Tyres;

Federal Motor Vehicle Safety Standard,

FMVSS 109 New Pneumatic Tires;

49 CFR Part 571- Final Rule

Canadian Standards Association Standard,

CSA D238.3 - M1979 Tire retreading;

Irish Standard,

I.S. 412:1988 Retreaded passenger car and commercial vehicle tyres; and

American Society for Testing and Materials Standard,

ASTM F421 - 95b Standard method for measuring groove and void depth in passenger car tires.

Annexes A, B, C and D form an integral part of this Trinidad and Tobago Standard. Annex E is included for information purposes only.

Introduction

This standard is the third revision of the pneumatic tyres standard TTS 266: 2002 Specification for Pneumatic Tyres for Passenger Cars.

The first revision was as a result of a need to keep apace with new technology and the unfair trade practices brought about by trade liberalisation in Trinidad and Tobago.

Trade liberalisation had brought an influx of used tyres into the country, which competed unfairly with the other established tyre products, namely new, retreaded and regrooved tyres. There were no trade restrictions with regard to the quality of the used tyres and therefore consumers were under the perception that they were purchasing a quality product. The risk involved was that the used tyre might have contained defects that may not be detected by untrained consumers thereby making them a safety hazard to road users.

The first revision of this Trinidad and Tobago standard therefore addressed the concerns with used tyres by incorporating a section with detailed inspection and selection criteria. It also harmonised the standard with the industry accepted standard on tyres, the Federal Motor Vehicle Safety Standards standard, FMVSS 109, established in the United States, in order to facilitate international interchangeability and avoid costly and unnecessary duplication of tyre requirements.

This second revision incorporates technical revisions to the presentation, inspection and selection of used tyres. Annex C has also been added to provide a scientific and practical method for determining the average tread depth on used passenger car tyres in cases of dispute.

In formulating this standard cognisance was taken of the practices that are peculiar to the tyre industry and also of the need to follow international standards. Thus the use of the imperial (inch) system of units in some areas has been accommodated.

Tyres of apparently similar construction have different requirements as indicated by the units used in the marking of the tyres. This is the result of a parallel system that exists between users of the metric system of units and those of the imperial (inch system of units).

The third revision to this standard seek to address concerns raised by the Japanese Automobile Manufacturers Association (JAMA), and reduce the potential of any inherent technical barriers to trade being formulated between the major automobile supplier and Trinidad and Tobago. Section 10 of this revised standard addresses these concerns.

1 Scope

This standard applies to new and used pneumatic passenger car tyres.

This standard does not apply to retreaded or regrooved tyres, or to used tyres (casings) intended for the retreading or regrooving process.

Normative references

The following normative documents contain provisions, which, through reference in this text, constitute provisions of this document. The latest edition of the normative document referred to applies.

TTS 76-1 Requirements for labelling - General principles of labelling.

TTS 429 Definitions of terms used in the pneumatic tyre industry.

TTS 432 Code of practice for the storage of tyres, inner tubes and flaps.

Terms and definitions

For the purposes of this standard, the definitions in Trinidad and Tobago standard, TTS 429 Definitions of terms used in the pneumatic tyre industry shall apply. In addition to these, the following term and definition shall also apply:

3.1 tyre construction code means a system of indicating the direction the plies of a tyre are laid down to form the carcass of the tyre.

Tyre designation

1 Dimensional and constructional characteristics

The characteristics shall be indicated as follows:

This order shall be maintained.

2 Nominal section width

The nominal section width of the tyre shall be indicated in millimetres, ending either in (0( or (5(, so that in any one series of tyres with the same nominal aspect ratio, the values shall all end with (0( or all end with (5(.

3 Nominal aspect ratio

The nominal aspect ratio shall be expressed as a percentage and shall be a multiple of 5.

NOTE 1 The aspect ratio is one hundred times the ratio of the section height to the section width of the tyre.

NOTE 2 When the nominal aspect ratio is 82 for radial ply tyres, or 95 and 88 for diagonal ply tyres, these numbers may be omitted.

4 Tyre construction code

The tyre construction code shall be as follows:

← B for bias-belted construction;

← D for diagonal construction; and

← R for radial ply construction.

The use of another code letter (for example, in the case of a new construction type) shall first be remitted by importers and distributors to the Trinidad and Tobago Bureau of Standards for acceptance and inclusion in the above list.

5 Nominal rim diameter code

4.5.1 For tyres mounted on existing rims the code shall be as given in Table D.1.

4.5.2 For tyres requiring new concept rims, for safety reasons especially concerning mounting, the code number shall be equal to the nominal rim diameter, expressed as a whole number in millimetres.

NOTE New concept rims are rims that are substantially different in design to conventional rims.

6 Service conditions characteristics

The service condition characteristics or service description shall be as follows:

← load index;

← speed symbol; and

← maximum permissible inflation pressure.

Load index - The tyre load capacity corresponding to the service conditions specified by the tyre manufacturer shall be indicated by a load index taken from Table D.2. This indication is understood to be for a single mounting.

Speed symbol - The speed symbol shall be indicated by a letter taken from Table D.3 corresponding to the speed category.

Maximum permissible inflation pressure - The maximum permissible inflation pressure shall be indicated in psi or kPa.

NOTE Information regarding the relationship between load index and the maximum permissible inflation pressure may be obtained from the manufacturer or publications of organizations listed in annex A.

7 Other service characteristics

4.7.1 The word “TUBELESS” shall be used to characterise tyres that can be used without a tube.

4.7.2 The letter “T” immediately in front of the dimensional and constructional characteristics shall be used to characterise special temporary-use spare tyres.

NOTE Specific indications, as required, may be added to indicate:

a) the type of vehicle for which the tyre is primarily designed by using a symbol “P”, which is the symbol for passenger car tyres;

b) the temporary use of certain spare tyres using indications such as “TEMPORARY USE ONLY”;

c) the position of mounting;

d) the direction of rotation; and

e) the type of tread pattern.

Requirements for new tyres

1 General

5.1.1 Each tyre manufacturer shall ensure that a listing of the tyre specifications, and the rims that shall be used with each tyre that the manufacturer produces, is available to the public.

The listing shall be contained in publications, current at the date of manufacture of the tyre or any later date, of at least one of the organizations listed in annex A.

Each rim listing shall include dimensional specifications and a diagram of the rim.

5.1.2 Each tyre shall incorporate a tread wear indicator that will provide a visual indication when the tyre has worn to a minimum acceptable tread depth as recommended by the manufacturer.

2 Physical dimensions

The actual section width and overall width of each tyre measured in accordance with B.2 shall not exceed the section width and overall width specified in the listing in 5.1 by more than:

a) 7 %, for tyres with a maximum permissible inflation pressure of 32 psi, 36 psi or 40 psi; or

b) 7 % or 10.2 mm (0.4 in), whichever is the larger, for tyres with a maximum permissible inflation pressure of 60 psi, or 240 kPa, 280 kPa, 300 kPa or 340 kPa.

3 Tubeless tyre resistance to bead unseating

When tested in accordance with B.3, the applied force required to unseat the tyre bead at the point of contact shall not be less than:

a) 6 675 N for tyres with a designated section width of less than 155 mm;

b) 8 900 N for tyres with a designated section width of 155 mm or greater but less than 205 mm; or

c) 11 120 N for tyres with a designated section width of 205 mm or greater.

4 Tyre strength

When tested in accordance with B.4, each tyre shall meet the requirements for minimum breaking energy specified in Tables D.4a and D.4b and D.4c.

5 Tyre endurance

When the tyre has been subjected to the laboratory endurance test specified in B.5:

a) there shall be no visual evidence of tread, sidewall, ply, cord, inner-liner or bead separation, chunking, broken cords, cracking or open splices; and

b) the tyre pressure at the end of the test shall be not less than the initial pressure specified in B.5.2.

6 High speed performance

When the tyre has been subjected to the laboratory high speed performance test specified in B.6, the tyre shall meet all the requirements specified in 5.5 (a) and (b).

Sampling and testing to determine compliance

1 General

Samples shall be taken from tyres that meet the requirements specified in clause 4 for tyre size designation, type and maximum inflation pressure and the requirements of 5.1.

2 Sampling and testing

For the purpose of issuing a test certificate, the size of the sample for testing shall be representative of the lot under consideration.

Each test sample shall consist of the following:

a) one tyre for physical dimensions measurements, resistance to bead unseating test and strength test, which shall be performed in this sequence;

b) one tyre for the tyre endurance test; and

c) a third tyre for the high-speed performance test.

NOTE This standard makes no provision for statistical sampling, quality control or contractual arrangements. Where compliance with this standard is to be assessed on the basis of statistical sampling and inspection, an authority that is acceptable to the Trinidad & Tobago Bureau of Standards should determine the sampling plan.

3 Compliance

Where the samples taken in accordance with 6.2 and tested in accordance with annex B, and satisfy all other requirements of this standard, the lot shall be deemed to comply with the requirements of this Trinidad and Tobago Standard.

Presentation, inspection and selection of used tyres

1 Presentation of used tyres for inspection

It shall be the responsibility of the vendor or importer to ensure that the following requirements are met before presenting used tyres for inspection:

a) all used tyres that are fitted onto rims or the wheels of vehicles shall be removed from them; and

b) all used tyres shall be in a clean condition, that is they are dry and free from dirt or any foreign material that may hinder the inspection process.

2 Inspection of used tyres

Used tyre inspection shall be made by an inspector appointed by the Trinidad & Tobago Bureau of Standards. Each used tyre shall be inspected on its outside surface and then on its inside in order to detect any evidence of damage or defects. The inspection shall include distorting the natural contour of the tyre sufficiently for visual inspection under adequate lighting.

NOTE 1 It is recommended that electronic, ultrasonic or holographic casing inspection equipment be used as an aid in determining the integrity of a used tyre.

NOTE 2 The natural contour of the tyre may be distorted by manual or mechanical means for inspection.

3 Selection criteria for used tyres

7.3.1 A used tyre shall not be acceptable for motor vehicle use unless it has a minimum average tread depth of 4.0 mm. The minimum average tread depth shall be determined in accordance with the method set out in annex C.

7.3.2 A used tyre shall not be acceptable for motor vehicle use unless it conforms with the labelling requirements of clause 10.

7.3.3 A used tyre containing any of the following weaknesses, defects or characteristics shall not be accepted for motor vehicle use:

a) exposed cords due to tread wear or sidewall scuffing;

b) radial or groove cracks;

c) tread separation;

d) weather cracking;

e) broken, damaged, kinked or exposed bead wires;

f) any visual evidence of belt damage;

g) ply separation;

h) porous liners or defective or opened splices in liners extending to the cords;

i) loose cord on the inner ply;

j) damage to the inner or bead seating areas on tyres identified as tubeless;

k) evidence of having been used in an under-inflated or overloaded condition;

l) casing break-up (flex break);

m) generally weakened condition due to age, moisture, or exposure to oil or other chemical attack;

n) damage to the plies in the bead area;

o) sidewall separation;

p) nail hole or other defect greater than 6 mm in diameter;

q) nail hole within 90° of another or the presence of more than four nail holes.

r) regrooved;

s) winter tyres that show evidence that studs were used;

t) non-adjustable; and

u) blemished.

NOTE A tyre defect is interpreted to be the same as a tyre injury.

7.3.4 Each used tyre shall incorporate a tread wear indicator that will provide a visual indication when the tyre has worn to a minimum acceptable tread depth as recommended by the manufacturer.

Non-conforming tyres

New or used pneumatic tyres primarily intended for use on passenger cars, but which do not conform to the requirements of this standard, shall not be sold, offered for sale, imported or released for normal use into Trinidad and Tobago.

NOTE Non-conforming goods are dealt with in accordance with the provisions of the Standards Act No.18 of 1997 and the Standards Act Regulations.

Storage

New and used tyres shall be stored in accordance with the requirements of TTS 432 Code of Practice for the storage of tyres, inner tubes and flaps.

Labelling requirements

10.1 Each new or used tyre fitted onto passenger vehicles entering Trinidad and Tobago which satisfies either UN-ECE, FMVSS or JIS standards shall be exempt from the requirements stated in section 10.2 (d), 10.2 (g) and 10.2 (h).

10.2 Each new and used tyre shall have permanently moulded into or onto both sidewalls, in letters and numerals not less than 2.0 mm high, the relevant labelling information in accordance with TTS 76-1, Requirements for labelling - General principles of labelling.

The following information shall also be indicated:

a) the designation of the dimensional and constructional characteristics;

b) the designation of the load and speed characteristics;

c) the designation of other service characteristics;

d) maximum permissible inflation pressure;

e) the words “tubeless” or “tube type” as applicable;

f) sufficient information to allow the tyre to be identified as bias, bias belted or radial ply;

g) the generic name of each cord material used in the plies (both sidewall and tread area) of the tyre;

h) actual number of plies in the sidewall, and the actual number of plies in the tread area if different; and

i) a marking or symbol indicating that the tyre was originally manufactured to comply with a recognised international body or practice. An example of such a marking would be the DOT[1]) symbol, which, when placed on a tyre would indicate that the tyre complies with the Federal Motor Vehicle Safety Standard FMVSS 109 – New Pneumatic Tyres, of the United States.

EXAMPLE Typical tyre markings:

165/80 R 15 Marking of dimensional and constructional characteristics;

87 H Marking of load index and speed symbol (distinct location but in the vicinity of preceding marking);

Maximum inflation Location left to the discretion

pressure 240 kPa of the tyre manufacturer;

TUBELESS Location left to the discretion of the tyre manufacturer;

Polyester Location left to the discretion of the tyre manufacturer; and

2 ply Location left to the discretion of the tyre manufacturer.

where the characteristics of a tyre with these markings are described as follows:

165 Nominal section width equal to 165 mm;

80 Nominal aspect ratio equal to 80;

R Radial ply construction;

15 Nominal rim diameter code corresponding to 381 mm;

87 Load index corresponding to a tyre load carrying capacity of 545 kg;

H Speed symbol corresponding to a speed category of 210 km/h;

Maximum inflation The maximum permissible inflation pressure; pressure 240 kPa

TUBELESS Tyre to be used without a tube;

Polyester Type of cord material used; and

2 ply The number of plies in the sidewall and tread area.

10.2 On at least one sidewall, the required labelling information stated in 10.1 shall be positioned in an area between the maximum section width and bead of the tyre. The information shall be positioned on the tyre so that it is not obstructed by the flange of any rim that was designated for use with that tyre (see 5.1).

10.3 The location of the marking of the load and speed characteristics shall be distinct but in the vicinity of the marking of dimensional and constructional characteristics.

10.4 Other service characteristic markings (see 4.7), where used, shall be so positioned such that their proximity to any other service conditions characteristic markings shall not cause any confusion.

10.5 If the maximum inflation pressure of a tyre is 60 psi, the tyre shall have permanently moulded into or onto both sidewalls, in letters and numerals not less than 12.0 mm high, the words "inflate to no more than 60 psi". On both sidewalls the words shall be positioned in an area between the tyre shoulder and the bead of the tyre. In no case shall the words be positioned on the tyre so that they are obstructed by the flange of any rim designated for use with that tyre (see 5.1).

Annex A

(normative)

Organizations that publish listings of tyre and rim specifications

The Tire and Rim Association (USA);

The European Tyre and Rim Technical Organization (Belgium);

Japan Automobile Tire Manufacturers’ Association Incorporated (Japan);

Deutsche Industrie Norm (Germany);

Scandinavian Tire and Rim Organization (Scandinavia);

The Tyre and Rim Association of Australia (Australia); and

British Standards Institution (United Kingdom).

Annex B

(normative)

Test procedures for new tyres

B.1 Test rims

Tyres shall be tested on test rims specified for their size designations as determined from the listing in 5.1.

Test rims shall be such that they undergo no permanent deformation and allow no loss of air through the portion that comprises the tyre-rim pressure chamber.

B.2 Physical Dimensions

B.2.1 Apparatus

B.2.1.1 External caliper.

B.2.1.2 Diameter tape (pi tape).

B.2.1.3 Tyre pressure gauge.

B.2.2 Procedure

The physical dimensions of tyres shall be determined under uniform ambient conditions as follows:

a) mount the tyre on a test rim and inflate it to the applicable pressure specified in Table D.5;

b) condition it at ambient room temperature for at least 24 h;

c) readjust pressure to that specified in B.2.2 (a);

d) caliper the section width and overall width at six points approximately spaced equally around the tyre circumference;

e) record the average of the measurements as the section width and overall width respectively; and

f) measure the tyre outer diameter.

B.3 Tubeless tyre bead unseating resistance

B.3.1 Apparatus

Bead unseating fixture as shown in Figure D.1.

B.3.2 Preparation of tyre wheel assembly

Wash the tyre, dry it at the beads, and mount it without lubrication or adhesives on a clean painted test rim.

Inflate it to the applicable pressure specified in Table D.5 at ambient room temperature.

Mount the wheel and tyre in the fixture as shown in Figure D.1 and force the standard block in Figure D.2a or Figure D.2b against the tyre sidewall as required by the geometry of the fixture.

If a tyre with an inflation pressure of 60 psi is being mounted then the bead unseating block in Figure D.2b shall be used.

B.3.3 Procedure

Apply a load through the block to the outer sidewall of the tyre at the distance specified in Figure D.1 for the applicable wheel size at a rate of (50 ( 10) mm/min, with the load arm substantially parallel to the tyre and rim assembly at the time of engagement.

Increase the load until the bead unseats or the applicable value specified in 5.3 is reached.

Record the maximum load applied.

Repeat the test at not less than four places that shall be equally spaced around the tyre circumference.

B.4 Tyre strength

B.4.1 Apparatus

B.4.1.1 Testing machine that incorporates a (19 ( 2) mm diameter cylindrical steel plunger with a hemispherical end which can be forced radially into a tread of a tyre while the force and the distance travelled by the plunger are indicated and recorded.

B.4.1.2 Tyre pressure gauge.

B.4.2 Preparation of tyre

Mount tyre on a suitable test rim and inflate it to the applicable pressure specified in Table D.5.

Condition it at room temperature for at least 3 h.

Re-adjust the pressure to what was specified in Table D.5 immediately before testing.

B.4.3 Procedure

Force the hemispherical end of the cylindrical steel plunger perpendicularly into the tread rib as near to the centre-line as possible, avoiding penetration into the tread groove, at the rate of (50 ( 10) mm/min.

Record the force and penetration at five test points equally spaced around the circumference of the tyre. If the tyre fails to break before the plunger is stopped by reaching the rim, record the force and penetration as the rim is reached, and use these values in the calculation of the breaking energy value. In the latter case, if the calculated value is less than the minimum breaking energy, the minimum breaking energy shall be deemed to have been achieved at that point.

Compute the breaking energy value W (Nm) for each test point by means of the following formula:

[pic]

where

F is the force (N); and

P is the penetration (m)

Determine the breaking energy value for the tyre by computing the average of the five values obtained from the above formula.

B.5 Tyre endurance

B.5.1 Apparatus

Laboratory test roadwheel that consists of a 1708 mm diameter flat-faced steel wheel against which a tyre and wheel assembly is pressed at specific loads.

B.5.2 Preparation of tyre

Mount a new tyre on a test rim and inflate it to the applicable pressure specified in Table D.5.

Condition the tyre assembly to (38 ( 3) °C for not less than 3 h.

Re-adjust the tyre pressure to what was specified in Table D.5 immediately before testing.

B.5.3 Procedure

Mount the tyre and wheel assembly on a laboratory test road wheel and press it against a steel test wheel at least as wide as the section width of the tyre to be tested.

NOTE An equivalent test wheel that is approved by the Trinidad & Tobago Bureau of Standards may be used with the applicable test load being a percentage of the load capacity as indicated in Table D.6 for the tyre’s size designation, type and maximum permissible inflation pressure.

During the test, the ambient temperature shall be (38 ( 3) °C.

Conduct the test with the test wheel speed at 80 km/h in accordance with the schedule in Table D.6 without pressure adjustment or other interruptions.

Immediately after running the tyre for the required time, measure its inflation pressure. Allow the tyre to cool for 1 h. Then deflate the tyre, remove it from the test rim, and inspect it for the conditions specified in 5.5 (a).

B.6 High speed performance

B.6.1 Apparatus

See B.5.1.

B.6.2 Procedure

After preparing the tyre in accordance with B.5.2, mount the tyre and wheel assembly in accordance with B.5.3 and press it against the test wheel with the load of 88 % of the tyre’s maximum load rating or load index as marked on the tyre sidewall.

Break in the tyre by running it for 2 h at 80 km/h.

Allow it to cool to (38 ( 3) °C and re-adjust the inflation pressure to the applicable pressure specified in Table D.5.

Without further re-adjusting the inflation pressure, continue test without interruption at test wheel speeds of 120 km/h for 30 min, 130 km/h for 30 min, and 140 km/h for 30 min.

Immediately after running the tyre for the required time, measure its inflation pressure. Allow the tyre to cool for 1 h. Then deflate the tyre, remove it from the test rim, and inspect it for the conditions specified in 5.5 (a).

Annex C

(normative)

Test method for determining the average tread depth of used passenger car tyres

C.1 Apparatus

The apparatus shall consist of a mechanical (or electromechanical) depth gauge fitted with a foot through which a spindle passes. The foot may have any of a variety of shapes, including but not limited to cylindrical, semi-cylindrical and rectangular. The reference surface of the gauge foot shall be ground planar and perpendicular to the gauge spindle. A diagram of a mechanical depth gauge is shown in Figure D.3.

The smallest scale division on the gauge shall be no more than 1 mm.

The gauge spindle shall extend at least 25 mm beyond the reference surface of the foot. Spindles may have any variety of shapes and diameters suitable for the tread depth to be measured.

The spindle shall not touch the side of the hole in the foot.

C.2 Preparation

C.2.1 Depth gauge

The gauge shall read zero when the foot is placed against a non-deformable flat surface, such as a glass plate, before any set of measurements is taken.

C.2.2 Tyre

The tyre shall be dry and free of any foreign material that would interfere with accurate measurements.

C.3 Procedure

C.3.1 Tyres with uniform wear

Place the foot of the gauge so that it bridges adjacent ribs over the area to be measured, avoiding tread wear indicators, so that the spindle makes perpendicular contact with the base of the groove as shown in Figure D.3. This single measurement characterises the groove depth at this location.

C.3.2 Tyres exhibiting irregular wear

Proceed in accordance with C.3.1, except the spindle does not have to make perpendicular contact at the base of the groove as shown in Figure D.4.

C.4 Average tread depth for the whole tyre

C.4.1 Location of tyre measurements

Measurements shall be made along two outer circumferential grooves and along either the centre circumferential groove or, in the absence of a centre circumferential groove, along two circumferential grooves adjacent to the centreline of the tread.

C.4.2 Number of measurements

At least one measurement shall be taken in each quadrant of each of the circumferential grooves identified in C.4.1.

C.4.3 Average tread depth

The average tread depth shall be the arithmetic mean of all measurements taken on the tyre.

Annex D

(normative)

Tables and figures

Table D.1 — Rim code diameter

|Code |Nominal rim diameter mm |

|10 |254 |

|12 |305 |

|13 |330 |

|14 |356 |

|15 |381 |

|16 |406 |

|17 |432 |

|18 |457 |

|19 |483 |

Table D.2 — Correlation between load index (LI) and tyre load carrying capacity (TLCC)

|LI |TLCC kg |LI |TLCC kg |

|50 |190 | 90 | 600 |

|51 |195 |91 |615 |

|52 |200 |92 |630 |

|53 |206 |93 |650 |

|54 |212 |94 |670 |

|55 |218 |95 |690 |

|56 |224 |96 |710 |

|57 |230 |97 |730 |

|58 |236 |98 |750 |

|59 |243 |99 |775 |

|60 |250 |100 |800 |

|61 |257 |101 |825 |

|62 |265 |102 |850 |

|63 |272 |103 |875 |

|64 |280 |104 |900 |

|65 |290 |105 |925 |

|66 |300 |106 |950 |

|67 |307 |107 |975 |

|68 |315 |108 |1 000 |

|69 |325 |109 |1 030 |

|70 |335 |110 |1 060 |

|71 |345 |111 |1 090 |

|72 |355 |112 |1 120 |

|73 |365 |113 |1 150 |

|74 |375 |114 |1 180 |

|75 |387 |115 |1 215 |

|76 |400 |116 |1 250 |

|77 |412 |117 |1 285 |

|78 |425 |118 |1 320 |

|79 |437 |119 |1 360 |

|80 |450 |120 |1 400 |

|81 |462 | | |

|82 |475 | | |

|83 |487 | | |

|84 |500 | | |

|85 |515 | | |

|86 |530 | | |

|87 |545 | | |

|88 |560 | | |

|89 |580 | | |

Table D.3 — Correlation between speed symbol and speed category

|Speed symbol |Speed category km/h |

|J |100 |

|K |110 |

|L |120 |

|M |130 |

|N |140 |

|P |150 |

|Q |160 |

|R |170 |

|S |180 |

|T |190 |

|U |200 |

|H |210 |

|V |240 |

|Z |greater than 240 |

|NOTE The speed category denotes the maximum speed for which use of the tyre is rated. |

Table D.4a — Minimum Breaking energy values for radial ply tyres

|Designated section |Minimum breaking energy values |

|width mm |for various maximum inflation pressures |

| |Nm |

| | 240 kPa |280 kPa |300 kPa |32 psi |36 psi |40 psi |

|Below 160 |220 |441 |220 |220 |330 |441 |

|160 and above |294 |588 |294 |294 |441 |588 |

|NOTE Values under psi units and values under kPa units are two internationally accepted parallel systems. |

Table D.4b — Minimum breaking energy values for bias ply tyres

|Designated |Cord material |Minimum breaking energy values for various |

|section width | |maximum inflation pressures |

|mm | |Nm |

| |

Table D.4c — Minimum breaking energy values for tyres with 60 psi maximum permissible inflation pressure

|Maximum load rating |Cord material |Minimum breaking energy values |

| | |Nm |

|Below 400 kg (880 lbs) |Rayon |186 |

| |Nylon or Polyester |294 |

|400 kg (880 lbs) and above |Rayon |113 |

| |Nylon or Polyester |220 |

Table D.5 — Test inflation pressures

|Maximum permissible inflation |240 kPa |280 kPa |300 kPa |340 kPa |32 psi |36 psi |40 psi |60 psi |

|pressure | | | | | | | | |

|Pressure to be used in tests for |180 kPa |220 kPa |180 kPa |220 kPa |24 psi |28 psi |32 psi |52 psi |

|physical dimensions, bead | | | | | | | | |

|unseating, tyre strength and tyre | | | | | | | | |

|endurance | | | | | | | | |

|Pressure to be used in test for |220 kPa |260 kPa |220 kPa |260 kPa |30 psi |34 psi |38 psi |58 psi |

|high speed performance | | | | | | | | |

Table D.6 — Applied load and respective time

|Duration |Percentage of the tyre load-carrying capacity (TLCC) |

|h |% |

|4 |85 |

|6 |90 |

|24 |100 |

Dimensions of "A" for tyres with the following maximum inflation pressures mm |60 psi |- |- |- |- |- |- |- |- |- |- |213 |226 |239 |251 |- | | |Other than 60 psi |216 |229 |235 |248 |254 |279 |292 |216 |229 |241 |254 |267 |279 |292 |305 | |Wheel Size |320 mm |340 mm |345 mm |365 mm |370 mm |390 mm |415 mm |10 in |11 in |12 in |13 in |14 in |15 in |16 in |17 in | |

Dimensions in millimetres (mm)

Figure D.2a — Bead unseating block

Dimensions in millimetres (mm)

Figure D.2b — Bead unseating block

Figure D.3 — Measurement of tread depth for uniform wear

Figure D.4 — Measurement of tread depth where irregular wear is exhibited

Annex E

(informative)

Recommended information to be supplied by the purchaser and the manufacturer or supplier

E.1 Recommended information to be supplied by the purchaser

It is recommended that the purchaser give the following information to the manufacturer or supplier at the time of order or enquiry:

a) the number of this Trinidad and Tobago Standard;

b) the designation of the dimensional and constructional characteristics;

c) the designation of the load and speed characteristics;

d) the designation of the other service characteristics;

e) the quantity;

f) whether or not the purchaser requires a Test Certificate; and

g) whether or not the purchaser requires inspecting the product at the manufacturer’s works.

E.2 Recommended information to be supplied by the manufacturer or supplier

When requested by the purchaser, it is recommended that the manufacturer or the supplier supply a certificate satisfactory to the Trinidad and Tobago Bureau of Standards showing results of the tests carried out to determine compliance of the new or used tyres with its specification.

-----------------------

[1]) Department of Transport of the United States of America

-----------------------

Nominal aspect ratio

Nominal section width

Tyre construction code

Nominal rim diameter code

R 317

146

10(

10(

MATERIAL: Cast Aluminium 355

T-6 Condition

FINISH: 1.3 Micrometer ((m)

68

Section B–B

Section A–A

R 25

457

A

A

B

B

Tangent

R 25

R 254

MATERIAL: Cast Aluminium 355

T-6 Condition

FINISH: 1.3 Micrometer ((m)

R 317

146

10(

10(

68

Section B–B

Section A–A

R 25

457

1.

A

B

B

Tangent

R 254

10(

39 (Ref.)

60(

41

R 25

R 213

211 to bottom of anvil

Pivot on centreline of beam

"A"

Dimensions in millimetres (mm)

Figure D.1 — Bead unseating fixture

465

Beam (Horizontal)

16

13

10

7

Gauge Scale

Groove

Gauge Foot

Rib

Spindle

Spindle

Rib

Gauge Foot

Groove

Gauge Scale

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